Novel compounds related to lincomycin,a process for making the same,and a process for converting them to lincomycin and lincomycin analogs

ABSTRACT

LINCOMYCIN IS FORMED BY TOSYLATING METHYL 1-THIO-A-DGALACTO-OCTOPYRANOSIDE TO FORM METHYL 6-O-(P-TOLUENESULFONYL)-1-THIO-A-D-GALACTOPYRANOSIDE, ACYLATING THE RESULTING COMPOUND TO FORM THE PERACYLATE, REPLACING THE TOSYL GROUP WITH IODINE TO FORM PERACYLATED METHYL 6-DEXY-6IODO-1-THIO-A-D-GALACTOPYRANOSIDE, REPLACING THE IODO GROUP BY A NITRO GROUP TO FORM PERACYLATED METHYL 6-DEOXY-6-NITRO-1-THIO-A-D-GALACTOPYRANOSIDE, TREATING THE LATTER WITH ACETALDEHYDE AND SODIUM METHOXIDE TO FORM METHYL 6-DEAMIN-6-NITRO-A-THIOLINCOSAMINIDE, REDUCING THE LATTER WITH LITHIUM ALUMINUM HYDRIDE TO FORM METHYL A-THIOLINCOSAMINIDE, AND ACYLATING THE LATTER WITH TRANS-1METHYL-4-PROPYL-L-2-PYRROLIDINECARBOXYLIC ACID. BY SUBSTITUTING OTHER ALDEHYDES AND/OR OTHER 1-THIO-A-D-GALACTOPYRANOSIDES, ANALOGS OF LINCOMYCIN ARE OBTAINED.

United States Patent 01 fice 3,681,321 Patented Aug. 1, 1972 US. Cl.260210 R 5 Claims ABSTRACT OF THE DISCLOSURE Lincomycin is formed bytosylating methyl l-thiO-oc-D- galacto-octopyranoside to form methyl6-0- (p-toluenesulfonyl)-1-thioa-D-galactopyranoside, acylating theresulting compound to form the peracylate, replacing the tosyl groupwith iodine to form peracylated methyl 6-deoxy-6- iodo 1thio-m-D-galactopyranoside, replacing the iodo group by a nitro group toform peracylated methyl 6-deoxy-6-nitro-1-thio-u-D-galactopyranoside,treating the latter with acetaldehyde and sodium methoxide to formmethyl 6 deamino-6-nitro-a-thiolincosarninide, reducing the latter withlithium aluminum hydride to form methyl u-thiolincosaminide, andacylating the latter with trans-1-methyl-4-propyl-L-2-pyrrolidinecarboxylic acid. By substituting otheraldehydes and/or other l-thio-u-D-galactopyranosides, analogs oflincomycin are obtained.

CROSS REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of my copending application Ser. No. 867,362, filedOct. 17, 1969 and now abandoned.

BRIEF SUMMARY OF INVENTION CH2NO2 0A0 VI methyl 2,3,4trl-O-aeetylD-galactopyranoside in which Ac is hydrogen or acetyl or likelower-carboxacyl, for example, lower-alkanoyl, benzoyl and the like, andMe is methyl or like lower-alkyl.

The novel compounds VIAc, that is, compound of Formula VI where Ac(Formula VI) is carboxacyl, are useful as intermediates for makinglincomycin and lincomycin analogs. The novel compounds VIH, that is,where Ac (Formula V1) is hydrogen, can be used to modify polyurethaneresins. Either as such or after condensation with ethylene or propyleneoxide, they can be added to the reaction mixture of polyol andpolyisocyanate and function therein as a cross-linking agent or as allor part of the polyol component.

The preparation of the novel compounds of the inven tion and thepreparation of lincomycin and lincomycin analogs therefrom are shown inthe following sequence:

CHzOH I ragga D-galactose CHzOH 11 KTiLELMQ methyl 1-thlO-a-D-galactopyranoside Step 1 MeSH CHeOTs IV no I- methyl 2,3,4-tri-O-acetyl-6-O-tosy1-1-thioa-D-galactopyranoside 0, y l I SMe methylfi-O-tosyl-l-thio-a-D- galactopyranosido III Step 3 HO i Nal Step 4 CHzIV methyl 2,3,4-tri-O-acetyl- 6-deoxy6-iodol-thio-a-D- galactopyranosideCHQNOZ VI methyl 2,3,4-tri-0-acetylo-deoxy-fi-nitro-l-thio-a-D-galactopyranoside ROHO lNaOMe Step 6 Step 5 NaNOa E on SMe

methyl a-thiolineosaminide and 7-epimer (R=methyl) vnr R No,- Step 7 HOLiAlH4 VII methyl G-deamino-G-nitro-athiolincosaminide and 7-epimer(R=methyl) PHAH (trans-l-methyl- Step 8 ipropylprollne) PHANH-Lineomycin and 7-epimer R methyl) pyrrolidinecarboxamido) 1 thio L threoa D galacto-octopyranoside, are separated.

The several steps generally are carried out by procedures already knownin the art. The mercaptolysis (Step 1) is a known process. Thetosylation (Step 2) is atypical, however, because only the 7-O-hydrogenis replaced. This is accomplished by the use of the stoichiometricamount of tosyl chloride (not more than excess) and keeping thetemperature low, say between about minus 5 C. and about plus 5 C.Pyridine or like tertiary base can be used as the solvent and acidacceptor. The acylation (Step 3) of the 2-, 3-, and 4-hydroxyls of thesugar can be effected by acetic anhydride or like acid anhydride inpyridine in the usual manner or by other known acylation procedures. Thereplacement of the tosyl group by iodine (Step 4) is effected withsodium iodide in acetone in the usual manner, and the replacement of theiodine by nitro (Step 5) is effected by sodium nitrite indimethylformamide to which phloroglucinol may be added to reduce sidereactions. Advantageously an excess of sodium nitrite is used, and thereaction is effected with gentle heating say to between about 50 C. andabout 75 C. Step 6 is an aldol-type condensation in which the a-hydrogenis activated by the nitro group instead of by a carbonyl, as in theSowden-Fischer synthesis. Step 7 is a standard lithium aluminum hydridereduction and Step 8 is an acylation by known acylation procedures, forexample, those disclosed in US. Pat. 3,380,992.

In place of the trans 1 methyl 4 propylproline, there can be substitutedother L-2-pyrrolidinecarboxylic acids, also in accordance with thedisclosure in Us. Pat. 3,380,992, whereby analogs of lincomycin and its7-epimer are obtained. Also in place of acetaldehyde (Step 6), there canbe substituted other aldehydes for example formaldehyde,propionaldehyde, butyraldehyde, benzaldehyde, or substituted aldehydesfor example salicylaldehyde, tolualdehyde, methylpentanal,nitrobenzaldehyde, or vanillin. For example if formaldehyde issubstituted, 8- norlincomycin, 6 (trans 1 methyl 4 propyl L- 2pyrrolidinecarboxamido) 1 thio L glycero u- D galacto heptopyranoside,is obtained. Similarly when propionaldehyde is substituted, there areobtained 8- homolincomycin, methyl 6,8,9 trideoxy 6 (trans 1- methyl 4propyl L 2 pyrrolidinecarboxamido)- 1 thio D erythro a D galactononopyranoside, and 8 homo 7 epilincomycin, methyl 6,8,9 trideoxy- 6(trans 1 methyl 4 propyl L 2 pyrrolidinecarboxamido) 1 thio L threo a Dgalactononopyranoside.

Ac in the above compounds represents a carboxacyl protective group ascommonly used in sugar chemistry. Ordinarily, it will be acetyl orbenzoyl, but can be any equivalent protective carboxacyl group. Wheneverdesired the Ac groups can be removed by base catalyzed hydrolysis. Me ismethyl or other lower-alkyl group. R is the radical of an aldehyde,RCHO, e.g., formaldehyde (R is hydrogen), acetaldehyde (R is methyl),propionaldehyde (R is ethyl), butyraldehyde (R is propyl), benzaldehyde(R is phenyl), salicylaldehyde (R is Z-hydroxyphenyl), tolualdehyde (Ris tolyl), methylpental (R is methylbutyl), nitrobenzaldehyde (R isnitrophenyl), or vanillin (R is 3-methoxy-4-hydroxyphenyl).

DETAILED DESCRIPTION OF THE INVENTION Example.Preparation of methyl6-deoxy-6-nitro-1-thiou-D-galactopyranoside and its peracyclate andtheir conversion to lincomycin and its 7-epirner Part A: D-galactosedimethyldithioacetal CHnOH SMe K... l SMo OH X To a solution of 25 g. ofD-galactose (I) in ml. of cone. hydrochloric acid cooled to 0 C. wasadded 25 g. of methanethiol. The reaction mixture was permitted to warmto room temperature and stirred for 17 hrs. The addition of 250 ml. ofethanol caused crystallization of D-galactose dimethyldithioacetal (X)which was collected by filtration, washed and dried. A yield of 13.5 g.(35% yield) of crude D galactose dimethyldithioacetal (X), M.P. 157-159C. was thus obtained. Recrystallization of 1 g. of this material frommethanol afforded 850 mg. of D-galactose dimethyldithioacetal (X), M.P.160163 C., [a] +6 (MeOH, c.=0.35). The mother liquors were pooled andreserved for part B.

An excess of lead carbonate was added to the alcohol filtrate, and themixture :was filtered. The filtrate was concentrated under vacuum to asmall volume at which point crystals formed. After cooling, the crystalswere collected, washed and dried. The crude crystals of D-galactosedimethyldithioacetal (X) weighed 7.7 g. Recrystallization of thisproduct from methanol gave 4.6 g. of D-galactose dimethyldithioacetal(X), M.P. 161-164 C.

Part B: Methyl l-thio-a-D-galactopyranoside (II).- The mother liquorsfrom the crystallization of D galactose dimethyldithioacetal in part A-lwere concentrated. This residue of 16.3 g. was acylated in the usualmanner with 50 ml. of acetic anhydride and 50 ml. of pyridine. The crudeacetates, weighing 20.7 g., were chromatographed over 2.1 kg. of silicagel using cyclohexanezethyl acetate 1:1) as the solvent system.

After a forerun of 4.4 1., successive 100-ml. fractions were collected.Fractions 52 through 67 were pooled and evaporated to dryness yielding4.6 g. of a mixture of the acetate of methyll-thio-a-D-galactopyranoside (II) and D-galactose dimethyldithioacetal(X). This mixture was dissolved in 50 ml. of methanol and 14 drops of a25% solution of sodium methoxide in methanol was added. After 50 minutesthe reaction mixture was treated with D0wex-50(H+), a crosslinkedpolystyrene nuclear sulfonic acid cation exchanger in the acid form,until neutral and then chromatographed over 500 g. of silica gel usingchloroformzmethanol (2:1) as the solvent system. After a forerun of 650mL, successive 50-ml. fractions were collected. Fractions 16 through 26were pooled and evaporated to dryness yielding methyll-thio-a-D-galactopyranoside (II).

Part C: Methyl 6-O-(p-toluenesulfonyl)-1-thio-a-D- galactopyranoside(HI) CHgOT.

At 0 C. 5.65 g. of tosyl chloride (p-toluenesulfonyl chloride) was addedto a solution of 6.0 g. of methyl 1- thio-a-D-galactopyranoside (II) in30 ml. of pyridine. The solution was maintained at 0 C. overnight andevaporated to dryness under vacuum. The residue was stirred with diluteHCl. The crystals of crude methyl 6-0-(p-toluenesulfonyl)-l-thio-u-Dgalactoside (IH) were collected byfiltration and dried to give 5.54 g. M.P. 132- 142 C. A portion wasrecrystallized from methanol. The melting point of methyl6-O-(p-toluenesulfonyl)-1-thioa-D-galactoside (III) proved to be highlydependent on the rate of heating. When heated at the rate of 2 C./min.,methyl 6 O (p toluenesulfonyl) 1 thio a D- 5 galactoside (IH) melted at139-140 C., sintered 1 36 C. Its [M in pyridine Was +183, c.=1.0.

Analysis.-Calcd. for C I-1 8 (percent): C, 46.14; H, 5.33; S, 17.60.Found (percent): C, 46.17; H, 5.86; N, 17.28.

Part D: Methyl 6-O-(p-toluenesulfonyl)-1-thi0-a-D- galactopyranoside2,3,4-tri-O-acetate (IV).Acylation of 4.54 g. of methyl6-0-(p-toluenesulifonyl)-1-thio-u-D- galactoside (HI) with 13 ml. ofpyridine and 13 ml. of acetic anhydride at room temperature for 17 hrs.yielded 4.9 g. of glassy methyl 6-O-(p-toluenesulfonyl)-thio-a-D-galactopyranoside 2,3,4-tri-O-acetate (IV).

Analysis.Calcd. for C H O S Mol. wt. 490. Found: M+ 490. (Molecular ion,mass spec.).

Part E: Methyl 6-deoxy-6-iodo-l-thio-a-D-galactopyranoside2,3,4-tri-O-acetate (V).-A solution of 19.5 g. of crystalline methyl6-O-(p-toluenesulfonyl)-1-thio-m-D- galactopyranoside2,3,4-tri-O-acetate (IV) and 15 g. of NaI in 200 ml. of acetone washeated in a glass bomb at 100 C. for 7.5 hrs. After cooling, the sodiumtosylate, which weighed 6.3 g. (82% was removed by filtration. Theacetone was distilled under vacuum. The residue thus freed of acetonewas partitioned between methylene chloride and dilute sodium bisulfitesolution and chromatographed over 1.1 kilograms of silica gel usingchloroformmethanol (6:1) as the solvent system. After a forerun of 2.1liters, successive SO-ml. fractions were collected. Fractions 2 through12 were pooled and evaporated to dryness yielding 9.29 g. of methyl6-(16OXY-6-i0d0-l-thiO-oc-D- galactopyranoside 2,3,4-tri-O-acetate (V)(51.2%) as a glass.

Part F: Methyl 6-de0xy-6-nitro-1-thio-u-D-galactopyranoside2,3,4-tri-O-acetate (VIAc) 0A0 VIAc A solution of 9.29 g. of methyl6-deoxy-6-iodo-1-thiou-D-galactopyranoside 2,3,4-tri-O-acetate (V), 4.6g. of NaNO and 4.6 g. of phloroglucinol in 300 ml. of dimethylformamidewas warmed at 65 C. (bath temp.) for 18 hrs. The solvent was evaporatedin vacuo. The residue thus freed of solvent was partitioned betweenmethylene chloride and water. The organic phase was percolated through1.1 kg. of silica gel using cyclohexaneacetone (2:1) for elution. Aftera forerun of 2.3 1., 50-ml. fractions were collected. Fractions 16through 24 were pooled and evaporated to dryness yielding 1.13 g.(14.8%) of crystalline methyl6-deoxy-6-nitro-l-thio-u-D-galactopyranoside 2,3,4-tri-O-acetate (VIAc)which when recrystallized from ethyl acetate-technical hexane melted at165172 C.

Analysis.Calcd. for C H NO S (percent): C, 42.73; H, 5.24; N, 3.83; M01.wt. 365. Found (percent): C, 42.67; H, 5.24; N, 3.74; M+ 365.

Part G:

METHOD A CH3 JHOH CHgNOa HNOz HO 1' HO Methyl 6 deoxy6-nitro-1-thio-a-D-galactopyranoside 2,3,4-tri-O-acetate (VIAc) (2.19g.) was suspended in 90 ml. of methanol and under N 0.7 ml. of a 25%solution of sodium methoxide in methanol was added over about min.Dissolution was complete and the mixture tested basic to indicatorpaper. Tlc (chloroform-methanol, 6: 1) showed hydrolysis to methyl6-deoxy-6-nitro-l-thio-a-D- galactopyranoside (VIH). Acetaldehyde (1ml.) and 0.2 ml. of a 25 solution of sodium methoxide in methanol wereadded, followed in 10 minutes by 1 ml. more acetaldehyde and 3 moredrops of the solution methoxide solution. The methanol solution wastreated successively with 2 portions of 10 g. of Dowex-SO resin (across-linked polystyrene nuclear sulfonic acid cation exchanger). Themethanol was evaporated and the residue chromatographed over 1.1 kg. ofsilica gel using chloroformmethanol (6: 1) as the solvent system. Aftera forerun of 500 ml., successive 10-ml. fractions were collected.Fractions 25 through 39 were pooled and evaporated to dryness yielding470 mg. (32.9%) of crystalline methyl 6- deoxy 6nitro-l-thio-u-D-galactopyranoside (VIH), M+ 239. \Fractions 49 through78 were pooled and evaporated to dryness yielding 547 mg. (32.2%) ofcrystalline methyl 6-deamino-6-nitro-a-thiolincosaminide and its7-epimer (VII), M+ 283.

METHOD B In the manner described in method A, the 470 mg. of methyl-6-deoxy-6-nitro-l-thio-a-D-galactoside (VIH) of method A was condensedwith acetaldehyde in methanol in the presence of sodium methoxide. Afterchromatography 280 mg. of crystalline methyl6-deamino-6-nitro-athiolincosaminide and its 7-epimer (VII) (50.3%) wasobtained.

Part H: Methyl u-thiolincosaminide and its 7-epimer (VIII) .--Methyl6-deamino-6-nitro-l-thio-a-lincosaminide and its 7-epimer (VII) (220mg.) from Part G was dissolved in 3 ml. of tetrahydrofuran and added to200 mg. of lithium aluminum hydride in 5 ml. of tetrahydrofuran. Thereaction mixture was stirred for 0.5 hr. at 20 C. and heated at refluxfor 0.75 hr. with cooling. A few drops of water were added and themixture filtered. Evaporation of the filtrate gave only 9 mg. of an oil.The filtration residue was washed well with water and lyophilized. Itwas then chromatographed over 20 g. of silica gel using methanol as thesolvent system. After a forerun of 40 ml., successive 2-ml. fractionswere collected. [Fractions 2 through 14 were pooled and evaporated todryness yielding 14 mg. of material containing methyla-thiolincosaminide and its 7-epimer (VIII).

Part I: Lincomycin (IXa) and its 7-epimer a o 1 l (L Me H IX To asolution of 63 mg. (0.3 mmole) of trans-l-methyl-4-propyl-L-2-pyrrolidinecarboxylic acid hydrochloride and 84 mg. oftriethyl amine in 6 ml. acetonitrile was added 42 mg. of isobutylchloroformate with cooling in an ice methanol bath. To this solutionthere was added a solution of 58 mg. of crude methyl a-thiolincosaminideand its 7- epimer (VIII), prepared according to Part B, in 3 ml. ofwater. After stirring for 1 hr. the reaction mixture was evaporated todryness in vacuo and the residue taken up in methylene chloride. Themethylene chloride extract after filtering over anhydrius sodium sulfatewas evaporated to dryness yielding about mg. of crude lincomycin. Thecrude lincomycin was chromatographed over 15 g. of silica gel usingchloroform-methanol (4:1) as the solvent system. After a 40 ml. forerun,l-ml. fractions were combined. Fractions 2, 3, and 4 were pooled andevaporated to dryness yielding a product containing both lincomycin andits 7-epimer. Fractions 5 through 19 were pooled and evaporated todryness yielding 6 mg. crude lincomycin as an oil. This was converted tohydrochloride and crystallized from aqueous acetone to yield crystallinelincomycin hydrochloride.

I claim:

1. A compound of the formula where Me is lower-alkyl and Ac is hydrogenor loweralkanoyl or benzoyl.

2. A compound according to claim 1 wherein Ac is lower-alkanoyl.

3. A compound according to claim 1 Where Ac is acetyl.

4. A compound according to claim 1 where Me is methyl.

5. A compound according to claim 1 Where Ac is acetyl and Me is methyl.

References Cited Wolfrorn et al.: Advances in Carbohydrate Chemistry andBiochemistry, vol. 24, 1969, Academic Press, NY, NY. pp. 98-99.

LEWIS GOTTS, Primary Examiner a J. R. BROWN, Assistant Examiner UNITEDSTATES PATENT OFFICE CERTIFICATE; OF CORRECTION 7 Patent No. 5, 681 521Dated Augus t 1 1972 Invencors) Barney J Mag er le in It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2, l ine ll-l, For "Step 3" read Step 5 v.

Ac 0 Ac 0 Column 6, l ine 6, for "solution methoxide solution" readsodium methoxide solution Signed and sealed this 9th day of January1973..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RbBERT GOTTSCHALK Attesting Officer Commissionerof Patents

